1. Field of the Invention
The present invention generally relates to computer networks. More particularly, the invention relates to electronic switches through which communications pass from one point in a network to another. Still more particularly, the invention relates a plurality of switching devices that are combined together in such a way as to virtualize a larger, multiport switch.
2. Background Information
Initially, computers were most typically used in a standalone manner. It is now commonplace for computers and other types of computer-related and electronic devices to communicate with each other over a network. The ability for computers to communicate with one another has lead to the creation of networks ranging from small networks comprising two or three computers to vast networks comprising hundreds or even thousands of computers. Networks can be set up to provide a wide assortment of capabilities. For example, networks of computers may permit each computer to share a centralized mass storage device or printer. Further, networks enable electronic mail and numerous other types of services. Generally, a network's infrastructure generally comprises switches, routers, hubs and the like to coordinate the effective and efficient transfer of data and commands from one point on the network to another.
Internetworking of high-performance computers has become the focus of much attention in the data communications industry. Performance improvements in processors and peripherals, along with the move to distributed architectures such as client/server configurations, have spawned increasingly data-intensive and high-speed networking applications, such as medical imaging, multimedia, and scientific visualization. Various protocols have been developed to provide the necessary communications capacity.
One such protocol is InfiniBand™. InfiniBand™ permits high data rates of 2.5 gigabits per second (“Gbps”) in each direction. An exemplary InfiniBand™ architecture is shown in FIG. 1. The InfiniBand™ architecture is designed around a point-to-point, switched input/output (“I/O”) fabric, that interconnects a plurality of end node devices 10 via connection “fabric” 12 comprising a plurality of switches 14. The end nodes 10 can range from I/O devices such as disk arrays and tape drives to complex host computers.
The InfiniBand™ switched fabric 12 provides a reliable transport mechanism in which messages are enqueued for delivery between end nodes. The InfiniBand™ protocol defines standard media and signaling conventions for transporting data in a serial fashion, provides error detection codes and a packet structure for transporting the data, and creates some standard services (e.g., subnet manager, subnet administrator). Details regarding the InfiniBand™ protocol can be found online at www.infinibandta.org.
The InfiniBand™ architecture can be scaled to provide for a relatively small or large numbers of nodes. As such, the switches 14 may be required to provide anywhere from a relatively few ports to a large number of ports. Semiconductor devices (“chips”) are available that provide a switching function. For example, Mellanox Technologies currently offers an 8-port switch called the InfiniBridge MT21108. Messages entering any one of the eight ports can be directed to any one of the other seven ports. A subnet manager 18 is also provided to configure the switches 14.
In the event a system architect designs an InfiniBand fabric using 8-port switches 14, for obvious reasons, an 8-port switch such as the MT21108 device is well suited for use in such a network. However, it may be desired for the switches 14 in the network to have more than eight ports. For example, 16-port switches 14 may be desired. Despite the desire, in this example, for 16-port switches, the switch devices available on the market may have less than 16 ports, such as the 8-port MT21108 switch device. Further, it is generally very expensive to develop and test a new switch device. Moreover, multiport switches 14 may be desired having more ports than currently available semiconductor switch devices provide. It may be cost and time prohibitive to develop new switch devices having the desired number of ports to match the continuously changing needs of network architects. A solution to this problem is needed.